tcs tire size question

[WOODY]

I am sick of bending expensive rims and want to increase the height aspect of my tires. I currently run 225/40/17 on the front and 285/35/18 on the rears. What i would like to change to is 225/45/17 fronts and 285/40/18 rears. Will this maintain an acceptable ratio for the TCS? My current tires have no problem.
thanks!
woody

 

[nsxtasy]

The 225/45-17 front size will probably rub A LOT. In fact, I'm surprised that the 225/40-17 doesn't rub.

I also don't recommend a 40-series rear tire, which results in a really large outer diameter, over 9 percent larger than stock, which is HUGE. Also slower acceleration (not that you have to worry about that, on your car ). I'm not sure whether that would rub, either, but the 285/40 is over an inch larger in diameter than 285/35 (which, in turn, is over an inch larger than your stock outer diameter). In any case, I would stick with a 35-series in the rear.

To answer your question, though, those two sizes 225/45-17 and 285/40-18, would probably not cause problems with TCS. But don't use the 225/40 front with the 285/40 rear, which definitely would cause TCS problems.

 

[WOODY]

There must be a way to get the fronts thicker without rubbing. Would a 215/45 rub on the front? I have 17 x 8 wheels on front. The wheel wells appear as though they could absorb the 1" larger diameter. 1/2 " all the way around doesn't seem as though it would cause problems, especially if I narrowed the fronts out a bit.

 

[nsxtasy]

There must be a way to get the fronts thicker without rubbing. Would a 215/45 rub on the front? I have 17 x 8 wheels on front. The wheel wells appear as though they could absorb the 1" larger diameter. 1/2 " all the way around doesn't seem as though it would cause problems, especially if I narrowed the fronts out a bit.

Well, you could always get a widebody kit. :biggrin:

I wouldn't count on 215/45-17 not rubbing, just because it may look like there's clearance. Remember, rubbing occurs, not usually when the car is going straight ahead at a steady speed - the clearances you see when the car is parked - but rather, when it is cornering, braking, or accelerating, all of which cause the suspension at different corners of the car to compress or unwind, and the turning also causes the front tires to need clearance in the direction that they turn.

The reason the clearances are so tight in front is because the designers wanted to make the interior comfortable, including allowing the driver's legs to extend straight ahead, rather than at an angle like some other high-end sports cars.

Why are you trying to put taller sidewalls on your tires, anyway? There's no performance benefit in doing so; in fact, it's a detriment.

 

[Elite]

I run a 235/40-17 front. Not sure of the outer diameter, but the rubbing isn't all that bad(only on full lock turns). This size may work for your proposed rear setup?

 

[nsxtasy]

What he says:

the rubbing isn't all that bad

What he means:

It rubs.

j/k... :biggrin:

 

[WOODY]

I am sick of bending wheels on chicago potholes

 

[Elite]

I am sick of bending wheels on chicago potholes

The 235/40-17 actually has a decent compromise on sidewall. I think it is what you would want. If it works for your outer diameter F/R ratio(with the 285/40-18), it may be a good option for you.

What is your time frame? I can take a pic of my front wheel/tire for you so you can see the size of the side wall with this size, if you are interested? Could probably have a pic for you in the next day or two.

 

[WOODY]

i am in no hurry, i have my pilot alpine snow tires on right now! :biggrin:
the pics would be appreciated, why would the 235 sidewalls help me out? isnt it just a wider tire?

 

[Elite]

i am in no hurry, i have my pilot alpine snow tires on right now! :biggrin:
the pics would be appreciated, why would the 235 sidewalls help me out? isnt it just a wider tire?

Well the side wall rating is a ratio based on the width of a tire. So a 215/40-17 will have a shorter side wall then a 235/40-17(thus the overall diameter will increase as well).

 

[nsxtasy]

Well the side wall rating is a ratio based on the width of a tire. So a 215/40-17 will have a shorter side wall then a 235/40-17(thus the overall diameter will increase as well).

Yup. For example, the sidewall height on a 215/40-17 tire is .40 * 215 mm = 86 mm.

I am sick of bending wheels on chicago potholes

That's generally a function of sidewall height; the higher the sidewall, the better the protection against damage from potholes.

If you don't have an aftermarket big brake kit in front, I would suggest you consider getting smaller wheels, such as 16"/17". You can gain a half inch in sidewall height for every inch smaller the wheel diameter, assuming you choose tire sizes that keep the outer diameter the same. I know it might not be the "look" you want, but it's easier to achieve taller sidewalls that way, without worrying about the rubbing problems that oversized tires on 17"/18" wheels incur.

For example, here are the calculated sidewall heights for the most commonly-used tire sizes on NSXs with 16"/17" and 17"/18" wheels. (Note that this does not account for the reduction in height due to the deflection of the tire by the pavement.)

Front:
205/45-16 - 92.25 mm
215/45-16 - 96.75 mm
215/40-17 - 86 mm

Rear:
245/40-17 - 98 mm
255/40-17 - 102 mm
255/35-18 - 89.25 mm
265/35-18 - 92.75 mm

 

[WOODY]

It looks like the increased width of my current tires is giving me the equal sidewall height as the narrower 16/17 wheels would. It doesnt seem that 4 0r 5 mm would provide a whole lot of additional protection to the wheels. May be just run my tires at 50 PSI to raise them up1:biggrin:

 

[Elite]

Sorry it took a few days, and even then, I didn't take a pic. But I had someone else take a camera pic while at the shop. I will try to take a better shot from straight on next time I'm there.

 

[CarCrazed4Life]

I am sick of bending expensive rims and want to increase the height aspect of my tires. I currently run 225/40/17 on the front and 285/35/18 on the rears. What i would like to change to is 225/45/17 fronts and 285/40/18 rears. Will this maintain an acceptable ratio for the TCS? My current tires have no problem.
thanks!
woody

Do you mind me asking which rims you have? Sometimes expensive rims can still be not as strong as some others. 215/40/17 are some decent tires size wize for us NSX guys. 225/40/17s are only produced by Nitto, but then you have to change the rear out. 235/40/17 is also another option, but you will most likely rub with those. And 245/35/17 won't rub if and only if you have the perfect offset and I haven't found that yet without sticking past the wheel well to much

Your best bet is not to play with tire sizing, but wheel selection. Then Suspension tuning. I've bent SSR GT3s which were expensive, but to begin with they had a reputation for not holding up as well. I've bent cheap Privat Netz (which are the grade of HP Evos IMO.) I haven't had problems with most forged wheels which are usually lighter as well. Air Pressure is key.

But for all of those things, I'd try wheel selection over tire selection first.

 

[WOODY]

I have volk gtc rims. I like them and do not want to spend another $2500 to change rims/wheel sizes. Are there tires with sidewalls that have more plys? I know the tires my scout have more plys than normal for running low pressure in the sand dunes.

 

[CarCrazed4Life]

I have volk gtc rims. I like them and do not want to spend another $2500 to change rims/wheel sizes. Are there tires with sidewalls that have more plys? I know the tires my scout have more plys than normal for running low pressure in the sand dunes.

I remember reading (on these forums I beleive) that a few people have complained about Volk lately because they recently switched to forged centers, and cast barrels or vise versa. Their multi-peice wheels are not forged completely, and some have been having issues because of it. Rare, but they are starting to appear.

I would say the most cusion you are going to find in a 17" tire is a 235/40/17, but what offset do you have? Doing that in the front might make you want to consider 275/35/18 in the rear as your TCS threshold remains close to stock at 4.8% versus OEM 4.7%. A 215/45/17 is still .2" taller then a 235/40/17, and I've noticed height of the tire causes more chances of rubbing then width if the offset is there to compensate the width of the tire.

 

[rasir_x]

here is my LE-37's 235/40/17 & 285/30/18
(rubs only at full lock)

 

[Elite]

rasir_x, did you happen to buy that car from a MN seller?

Also, Woody, the pic I posted kinda looks like crap, I'll take a better/more flattering pic of the side profile of the car/wheels.

 

[WOODY]

Where exactly is it likely to rub at full lock? And is the first place to rub the inside front corner of the tires? I believe I have a +43 offset on the front. It sure looks like I could go up a size on the sidewalls, i have minimum 2" clearance all the way around, nut that is with the tires straight forward.

 

[rasir_x]

rasir_x, did you happen to buy that car from a MN seller?

Yes, I bought it from a friend of mine from up there. I pulled a lot out of it and put a lot back into it. Btw when you guys had the comptech harness bar out for you template/jig you were making. The bar was not reinstalled properly and the seltbelt carrier was dropped down inside and i had to fish it out. Currently I'm trying to find a place to repair the carrier bolts for the seatbelts but can't find anyone who can. You wouldnt know anyone able?

 

[Elite]

Yes, I bought it from a friend of mine from up there. I pulled a lot out of it and put a lot back into it. Btw when you guys had the comptech harness bar out for you template/jig you were making. The bar was not reinstalled properly and the seltbelt carrier was dropped down inside and i had to fish it out. Currently I'm trying to find a place to repair the carrier bolts for the seatbelts but can't find anyone who can. You wouldnt know anyone able?

Sorry, no I don't.

And I think a fellow prime'r reinstalled the bar at the shop.:redface: I don't remember the circumstance(it's been a while), but there was a reason why I didn't do it myself.

 

[Elite]

OK, so here are a couple better pics of the tires/wheels. I think these profiles could work for you in Chicago. But the car is filthy from collecting dust for too long and getting wet a little.:redface: I promised better pics, so here they are:

 

[WOODY]

OK, here is what I would like to try. azenis rt-615's

on my front volk gt-c with +43 offset I would like to cram a 225/45r/17
on the rear with +38 offset I would like to put a 295/40r/18

a couple questions.... is there a definative way to KNOW if they will rub? I currently have 225/17 fronts and 285/18 rears and have never had a rub....ever. By viewing the wheel well it appears I have plenty of room for an extra centimeter diameter. I understand that during heavy breaking and turning the clearances change, but if I have never rubbed now can I assume that at worst I may have a slight rub with only an added centimeter?

Thanks for the help gents!

 

[nsxtasy]

225/45-17 and 295/40-18 are likely to encounter TCS problems, due to the almost 5 percent difference in front-to-rear ratio. (The front diameter is 5.7 percent larger than stock, and the rear is 10.4 percent larger than stock.)

 

[marshmi]

I have GTC's on a 2001 with stock suspension. The fronts are 17x8 with +41 offset and the rears are 18x10 with +43 offset. When I bought the wheels they can with tires. The fronts were Potenza SO-3 225/45/17, and they rubbed. I replaced them with Goodyear F-1's, 215/45/17 and they DON"T rub. I am leaning on keeping the rears at 295/35/18, but switching from Ecsta's to F-1's.